Diagnostic devices are used to detect an analyte in a sample. The present invention relates to diagnostic devices and methods. In one particular embodiment, the present invention relates to diffraction-based diagnostic devices that can be used to detect one or more analytes present in a medium by detecting diffraction of an analyte/binder complex. These diffraction-based devices comprise a surface upon which is printed in a pattern a binder. Upon attachment of analyte to the binder that is printed in a pattern on the surface, diffraction of light that is transmitted through or reflected off of the printed surface occurs via the physical dimensions and defined placement of the binder.
U.S. Pat. No. 4,992,385 to Godfrey, et al. describes a method of preparing a diffraction grating from a thin polymer film for subsequent use as a sensing device. The sensing device described in U.S. Pat. No. 4,992,385 requires the use of a spectrophotometric technique to detect changes in the device's optical properties due to analyte binding. The device and method described in U.S. Pat. No. 4,992,385 require a complex detection method to detect changes in the diffraction pattern because changes in a diffraction pattern are more subtle than the qualitative determination that is made to determine whether a diffraction image is formed or is not formed.
U.S. Pat. No. 5,196,350 to Backman et al. describes an optical detection method for detecting the presence of specific ligands. The method described in U.S. Pat. No. 5,196,350 is an optical detection method for detecting specific ligands that requires a mask comprising slits to produce a diffraction pattern. An immunoassay device is placed between the mask and light source, so that binding by an analyte causes a change in the diffraction or interference pattern caused by the mask. Again, this method also requires a complex detection method to detect changes in a diffraction pattern and confirm the presence of a ligand.
International Publication No. WO 94/13835 describes a method and a system to detect biological macromolecules via diffraction of light from a probe of predetermined dimensions that diffracts light in a known pattern. The probe comprises an active surface that is able to highly concentrate the macromolecules relative to their concentration in the sample solution. The method and the system described in WO 94/13835 also require the use of a complex detector and an analyzer in order to detect changes in the diffraction pattern produced by the probe.
U.S. Pat. No. 6,261,519 describes a diagnostic device for measuring the concentration of an analyte in a sample. The device comprises a sample port at one end for introducing a sample. The device also comprises a bladder at the other end that must be depressed, inserted into a liquid sample and released to draw a sample. The device described in U.S. Pat. No. 6,261,519 does not further draw the sample past a test site to clear the test site so that diffraction or non-diffraction at the test site can be determined.
The methods, systems and devices discussed above do not provide a means for directing a sample to a test surface and then clearing the test surface of sample so that diffraction or non-diffraction can be determined. Furthermore, the prior art fails to provide a device in which a user of the device can control the position of a sample with in the device. What is needed is a simple, easy to use method, system and device for detecting an analyte that provides a means for directing a sample to a test surface and then clears the test surface of enough sample so that diffraction, and binding, can be accurately determined and allows a user of the device to control movement and incubation or reaction time of a sample within the device.